This invention relates generally to raised pavement markers which are embedded in pavement and more particularly relates to a raised marker which is depressible when struck by a passing snowplow or wheel and is provided with a spring return means which additionally prevents freezing and inhibits contamination of the marker.
The present invention also relates to self illuminating and locational pavement markers for use in marking roadway surfaces.
A series of traffic markers are often spaced along roadway for guiding vehicles into orderly lanes in order to create efficient traffic flow patterns and maintain a safe spacing of vehicles. Typically, the markers are embedded in or otherwise secured to the surface of the pavement and have a portion which protrudes upwardly above the pavement. This protruding portion carries a reflector sufficiently above the pavement so that rain water will not cover the reflector. This allows light from vehicle headlights to be reflected back to the driver making the markers clearly visible. This protrusion above the pavement surface also enhances the safety features of the marker because a longitudinal series of such markers will cause a series of thumping vibration noises which are both heard and felt by a driver and therefore provide a warning indication to the driver that he has strayed from the proper course.
Although such elevated markers are desirable for the above reasons, it must be accomplished with a structure which will not cause damage to a vehicle or which itself will be damaged in the ordinary course of its use. It is desirable that, neither tire damage nor marker damage should occur when the marker is driven over by a vehicle.
Furthermore, in those regions where ordinary winter snowfalls require periodic scraping of the highway with a scraper blade, the scraper blade should not damage the protruding marker. The marker should be able to withstand regularly repeated blows by the snowplow blade without any damage to the marker or any detrimental effect upon the snowplow itself or upon snowplowing efficiency.
As a result of these needs there have been a variety of designs of retractable markers. The retractable marker, although it protrudes above the highway also may be depressed by the incident blow of a snowplow blade or vehicle tire. Typically, a beveled upper surface formed on the protrusion provides an inclined plane across which the blade or tire rides deflecting the protruding portion of the marker downwardly to its withdrawn position.
A variety of different markers have been shown in the prior art. Some depend upon the flexing of a portion of the marker structure to permit the deflection and withdrawal of the protruding portion of the marker. Unfortunately, such flexing over a period of time and upon exposure to the deteriorating effects of sunlight has a tendency to cause cracks and breakage eventually resulting in the total destruction of at least the protruding portion of the marker.
As a result, the cylinder and piston-type markers are preferable inasmuch as they can be rigidly and strongly constructed, do not depend upon the flexing of exposed materials and still provide the advantages described above. They have, however, suffered from the difficulties that a cavity or void is of necessity formed within the cylinder and beneath the piston into which the piston moves when depressed by a vehicle tire or snowplow. Unfortunately, the cavity is subject to the collection of rainwater or snowmelt water and subsequent freezing on cold days or nights. Such freezing of accumulated water may render the piston-type unit inoperable. The piston cannot be moved downwardly into a space occupied by ice and thus it may be destroyed as a result of snowplowing operations. The inclusion of relatively large voids within such a marker and the resulting formation of relatively thick ice masses also can cause structural damage to the marker as a result of expansion of the freezing water.
In addition, piston-type markers have interfacing, sliding surfaces between the piston and cylinder which are subject to the collection of highway dirt and grit which can hinder the retraction of the piston. The cavity below the piston also can collect dirt or solid particulate matter which will produce the same effect as ice. The dirt is collected because each time the piston is depressed, air is exhausted from the cavity and then when the piston is released, air-borne or water-borne highway dirt is inhaled into the cavity.
In addition, roadway markers used in the past have generally been reflectorized and not self-illuminating which would be advantageous in certain applications. Illuminated markers of the past, such as those used at airports, require some type of power source such as an underground interconnecting wiring system. This requirement, which may be suitable for relatively short road surfaces such as air strips where power and/or regular maintenance is readily available, has not been generally accepted or adopted for general use on highways or other general road surface installations. In addition, these markers may require installation at the time of construction of the roadway because of the installation of wiring which may be necessary to institute such a system.
Location markers have also become common along modern roadways. These locational markers are commonly known as "mile marker" signs which are placed at one mile intervals along the roadway. These locational markers allow a motorist or emergency vehicles to ascertain their approximate position along the roadway. However, in order to take advantage of these markers the motorist must be able to see the roadway marker. Generally, this is not a problem, but a motorist who has car trouble may not be able to take advantage of the markers to locate his position unless he is within sight of the sign. Also the necessity of these markers alone adds increased clutter to the roadways and increases maintenance costs for replacement of the signs subsequent to accidents or as a result of environmental deterioration.
There is therefore a need for improvements in the piston-type traffic marker which can overcome the above problems.
According to the present invention there is provided an improved, depressible, reflective traffic marker. The traffic marker includes a base receptacle adapted to be secured within a cavity formed in a pavement or roadway surface. A piston is moveably disposed within the base and has a portion which normally protrudes above the base and the pavement surface. The piston contains reflector surfaces appropriately oriented relative to the traffic lanes and is resiliently depressible downwardly into the base. Also provided is a resilient, compressible, substantially water impervious mass which substantially fills all the space within the base and the interior of the piston assembly so as to prevent accumulations of water as well as to resiliently bias the piston upwardly so it protrudes above the pavement surface and base receptacle.
While the piston is designed and constructed in such a manner as to resist damage from vehicles, plows, etc. for an extended period of time, the depressible marker of the present invention is designed to enable quick and easy replacement of the piston should damage thereto impair its operational effectiveness.
Thus, the present invention provides a highly durable, relatively inexpensive depressible pavement marker which may be easily and quickly installed in existing roadway surfaces and is particularly well suited for use in climates requiring frequent clearing of snow therefrom.
In some applications it is difficult to position reflectors provided on such pavement markers as the present invention so as to be totally effective in returning light to the vehicle operator such as for example along a bend in a highway. Additionally there exist many other applications where lane markers may be desirable but an adequate source of light is not available to render reflectors effective. Thus according to another embodiment of the present invention there is also provided a self-illuminating retractable traffic marker. This marker also includes a base receptacle and a depressible piston. The piston includes a self contained light source and a power source such as a rechargeable battery for powering the light. A solar cell may be openly positioned on the piston for recharging the battery from available sunlight during daylight hours. A suitable photosensitive switch means is provided which responds to ambient light levels so as to activate and deactivate the internal light source between night and daylight hours respectively.
In some other applications, it may be desirable to incorporate means to advise emergency or police vehicles or the like of their present location. Accordingly in yet another embodiment of the present invention, a suitable transmitter may be provided capable of transmitting a suitably coded signal which upon receipt by a suitable vehicle mounted decoder may advise the operator of the precise present location of the vehicle. Such devices could be extremely useful to police and other emergency vehicles as an aid in providing services to accident scenes or the like or even on board computer tracking systems presently being considered for inclusion in vehicles of the future.
It is an object of the present invention to provide a depressible marker which is impervious to the elements normally encountered on a roadway surface and is effectively able to resist damage resulting from snow removal vehicles.
It is a further object of the present invention to provide a replaceable piston assembly for simplified replacement of a roadway marker.
Still further it is an object of the present invention to provide a self-illuminating lighted marker which will turn itself on under low light conditions or when otherwise signaled to do so and will recharge itself during daylight hours.
It is further an object of the present invention to provide an improved road marker, system which will provide instant information regarding a marker or a vehicle's position along a roadway surface.